I've been spending some time perf testing OL 2.4 in relation to OL 2.3.
Unfortunately, RE24 is noticeably slower than 2.3 was. Results of simple
auth testing with slamd show:
OL 2.3: 21,745 auths/second
OL 2.4: 15,733 auths/second
So OL 2.4 is 6,000 auths/second (aka 12,000 searches/second) slower than
2.3. I.e., 27% slower.
Howard committed a patch that slightly helps some situations, and
Hallvard has a rewrite of part of the lber library that I've been testing
that he'll commit soon. That helps somewhat:
OL 2.4 with howard and hallvard's patches: 17,086 auths/second.
That still leaves us over 4,500 auths/second (or 9000 searches/second)
slower than RE2.3. I.e., 21.5% slower. Which is quite a substantial gap.

Here are the numbers with --enable-debug=no.
OL 2.3: 22,356 auths/second
OL 2.4: 17,396 auths/second
So for 2.3, this is an improvement of 611 auths/second. For 2.4, this is
an improvement of 1,663 auths/second. Which I find rather significant. ;)

OK, that lends some weight to the idea that we have too many assert()s in the
2.4 code...